l. Field of the Invention
This invention relates to a skeletal joint prosthetic device and more particularly to knee and finger joints which have pretensioned or biasing spring means which provide them with predetermined and inherent controlled flexion.
2. Description of the Prior Art
In previous prosthetic devices the mechanical elements or components were designed primarily to provide the required free motion and were not designed to include any significant controlling or restraining of the intermediary phases of motion, once motion is started. For example, in a replacement knee joint, the joint is usually designed so that it is freely pivotal, within limits, and motion is provided solely by the muscular ability and coordination of the patient. The joint itself does not have inherent forces therein which aid or complement the existing available muscular ability and coordination of the patient.
Prior replacement finger joints are usually provided with a proper or natural curvature so that the hand may be employed to grasp some object when the object is inserted into the closed configuration of the hand. However, no muscular proportioning is accomplished between the natural resiliency of the finger prosthesis which is usually a silicone rubber or similar material implant, and the remaining muscle ability of the hand.
It has been discovered that an improved prosthetic joint may be provided by incoroporating a significantly pretensioned biasing means in the device the action of which can be correlated to the muscular ability of the patient.